1. Field of the Invention
The present invention relates to final rinse/dry systems for critical cleaning applications, and more particularly but not by way of limitation, to a final rinse/dry system to provide silicon wafers with dry, ultraclean surfaces. In one aspect the present invention relates to a final rinse/dry module for use with an ultrafiltration system to provide silicon wafers with dry, ultraclean surfaces substantially free of contaminants and surface microroughness.
2. Brief Description of the Prior Art
Systems have heretofore been proposed for preparing silicon wafers for oxidation and other treatments so that films having desired electronic properties can be formed on the surfaces of the wafers. However, such prior art systems have generally suffered from inherent defects which result in contamination of the surfaces of the wafers or uncontrolled chemical reactions which occur due to interaction of the prepared silicon wafer surface with the environment to which the silicon wafer is subjected. That is, the character of the surfaces of the silicon wafers often varies depending upon the position of the wafers in the system; and spray post dispensing of deionized water onto the wafers often causes a chemical reaction on hydrophobic silicon surfaces.
In the preparation of silicon wafers having ultraclean surfaces it is important that the surfaces of the wafers be free of native oxide and metallic impurities. Certain prior art systems employ a spinning rotor to enhance contact of the cleaning/rinsing solutions with the wafers during preparation of the wafers. However, spinning of a rotor on a metal bearing surface often results in metal contamination of the silicon wafer.
Native oxide and metallic impurities cannot be suppressed from the surfaces of silicon wafers if poorly optimized conditions are present on the wafer surfaces. Thus, in the final preparation of silicon wafers prior to critical processes, it is essential that the surfaces of the silicon wafers also be free of defect-generating mechanisms.
While advances have been made in systems for preparing silicon wafers, such advancements have generally been directed to reducing the cycle time for cleaning, drying and preparing the wafers, while sacrificing yield of the wafers due to contamination. Therefore, a need remains for an improved system for preparing silicon wafers which is cost effective, which permits the wafers to be rinsed and dried without exposure to widely varying dynamic conditions and sources of metallic contaminates or uncontrolled chemical reactions, and which overcomes the defects of the prior art systems. It is to such a system and rinse/dry module for the system that the present invention is directed.